Refrigerator frost indicator



Oct. 16, 1951 R, TQBEY 2,571,787

REFRIGERATOR FROST INDICATOR Filed July 12, 1946 2sHEE'rs-sHEET 1 Flt-3.5

WITNESSES: INVENTOR 1. F Payne/v05. Tau: Y.

ATTORNEY Oct. 16, 1951 R. EQTOBEY REFRIGERATOR FROST INDICATOR 2 SHEETS-SHEET 2 Filed July 12, 1946 INVENTOR WITNESSES:

H Y B ATTORNEY Patented Oct. 16, 1951 REFRIGERATOR FROST INDICATOR Raymond E. Tobey, Springfield, Mass., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 12, 1946, Serial No. 683,277

7 Claims.

This invention relates to refrigeration apparatus and more especially to a means for giving an indication when an objectionable amount of frost has formed on the cooling unit of the apparatus.

It is an object of this invention to provide a novel and inexpensive frost indicator.

This and other objects are effected by the invention as will be apparent from the following descriptionand claims taken in connection with l. the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a view of the upper portion of the interior of a refrigerator cabinet embodying the frost indicator of this invention, the indicator indicating that defrosting is unnecessary;

Fig. 2 is a view similar to Fig. l but with the defrost indicator indicating that defrosting is necessary; m

Fig. 3 is a sectional view substantially on the line III-III of Fig. 1, but with the door closed;

Fig. 4 is a view on the line IV--IV of Fig. 3;

Fig. 5 isa view similar to Fig. 4 but with the door open and showing the position of the indicator when defrosting is not necessary; and

Fig. 6 is a view similar to Fig. 5 but showing the position of the indicator when defrosting is necessary.

Referring tothe drawings for a detailed description of the invention, the reference numeral It indicates a refrigerator cabinet comprising an outer metal shell ii, an inner liner It, and heatinsulating material it interposed therebetween. A heat breaker strip ll closes the space between the inner and the outer shell at the front of the cabinet II, and a door It closes the access opening of the cabinet II. A cooling unit 24, provided with refrigerant tubing 28, is located in the upper portion of the cabinet II and provides a storage space for frozen foods.

The defrost indicator of this invention comprises an electric light bulb 28 located in a. domelike indentation a in the upper wall 32 of the inner liner It. A window It is provided in the upper wall of-the cooling unit directly below the light bulb 28 so 'that the interior of the cooling unit is illuminated. An opening 36 is provided in the breaker strip It of the upper'wall of the cabinet and opposite the light bulb 28. A window pane It carrying the legend Defrost" is positioned adjacent the opening 36 and a housing it joins the opening it with a second opening '42 in the indentation I. of the inner liner it. The housin It provides a light shaft between the light bulb "and the window pane 38 so that when the door II of the refrigerator is opened and the light bulb 2. is lit, the legend "Defrost" is clearly I visible.

A vertical shaft It is joumaled near one side of the housing til and is retained at its upper end by a pin 46 riding on the housing 40. The lower end of the shaft 44 projects through the upper wall 32 of the inner liner i4 and carries a paddle wheel 48 which is located closely adjacent the refrigerant tubing 26 so that a heavy coating of frost accumulating on the cooling unit 24 will interfere with the rotation of the paddle wheel 48.

A vane 50 is secured to the shaft 44 within the housing 40, and the shaft 44 and vane 50 are so located that by turning the shaft 44, the vane may be moved from a position in which it interrupts the light from the light bulb 28 through the housing 40 and in another position allows the light to pass through the housing 40 to illuminate the window 38. A spiral spring 52 is secured at one end to the shaft 44 and at the other end to the housing 40 and is stressed to rotate the shaft 44 to the position in which the vane 50 interrupts the light passing through the housing III. A disc 54 is positioned between the spiral spring 52 and the vane ill and carries an actuating arm 56. A push rod 58 projects through an opening in the breaker strip ll of the upper wall of the cabinet It to be actuated by the door 20 when the door 20 is moved to the closed position. The other end of the push rod 58 is slidably secured in a support it within the housing 40 and contacts the actuating arm 56, the spiral spring 52 biasing the arm 58 against the inner end of the push rod 58.

A switch contact 62 is secured to the rod It and comprises an L-shaped member 64 of electrical insulating material secured to the rod 58 and carries a metallic bridging member 66 at its extremity. Two electrical contact points 68 are so secured in the cabinet ID that they are bridged by thebridging member 66 when the rod it moves to its extreme righthand position as viewed in Fig. 4. The contact points .8 lie in one of the electric supply lines III of the light bulb 28. A spiral spring 12 on the shaft 58 is interposed between the support 60 and the insulating member 64 to bias the rod 58 towards the front of the cabinet ill. The spiral spring 12 also biases the bridging member 66 against the contact points 68 when the door 20 is open, thus lighting the lamp 28.

The actuating arm 56 is so located with respect to the vane and the push rod 58 that the push rod 58 moves the. vane 50 out of the path of light between the lamp 28 and the window 38, when the door 20 is closed. when the door 20 is opened, the spiral spring 12 moves the push rod 58 to the right as viewed in Fig. 4, causes the electric light bulb 28 to light, and releases 3 the actuating arm I. so that the vane 50 is moved by the spiral spring I to a position in which it interrupts the light from the bulb 2| to the window 3! provided there is not enough frost on the cooling unit 24 to engage the wheel 48. Under this condition, the legend "Defrost" will not be On the other hand, if the door is opened when a heavy layer of frost has formed on the cooling unit 24, the frost will prevent the rotation of the paddle wheel 48, and hence also the rotation of the shaft 44 so that the vane 50 does not interrupt the light from the bulb 28 to the window 38 and the legend Defrost" is illuminated on the window It. This is a signal for the user of the refrigerator that the cooling unit 24 requires defrosting.

The paddle wheel II is not fixedly secured to the shaft 44 but is merely in frictional engagement therewith sufficiently to prevent relative movement between the paddle wheel 48 and the shaft 44 under the bias of the spiral spring 52. This frictional engagement of the paddle wheel 48, however, aliows the door to be closed even though sufficient frost has accumulated on the cooling unit while the door 20 was open to e ge the paddle wheel and hold it stationary. U der these conditions, slippage between the paddle wheel 48 and the shaft 44 occurs as the shaft 44 is forcibly turned by the actuating arm 56. This is a safety feature to prevent breakage of the indicator.

It will be apparent from the above that this invention provides a simple signaling device for' a refrigerator cabinet which device indicates by the illumination of the legend "Defrost that the frost accumulation on the cooling unit 24 is sufficiently heavy to require defrosting. This illumination is effected only when the door is opened.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What I claim is:

1. In a refrigerator cabinet having a food storage chamber, a cooling unit having a surface ex-.

is moved from said closed position, at least said first position of said member being closely adjacent said surface of the cooling unit so that frost forming thereon retains said member in said first position against the action of said biasing means when said door is moved from its closed position, and means for indicating whether said member 4 4. In a refrigerator having a food storage chamber, a cooling unit having a surface exis retained in said first position when said door is moved from said closed position.

2. The apparatus defined in claim 1 in which the normally movable member comprises a portion of a wheel.

3. The apparatus defined in claim 1 in which said last-named. means interrupts a. light beam when said normally movable member is in said second position.

posed to the air of said chamber, an electric light bulb for illuminating the interior of said chamher, a door for said chamber, an object adapted to be illuminated by said light, bulb, a shaft journaled for rotation, a vane on said shaft, said shaft being adapted for rotation between a first position in which said vane does not interrupt a light beam from said bulb to said object and a second position in which said vane interrupts said light beam, means for biasing said shaft from said first position to said second position, an operating member responsive to the movement of the door for moving said shaft from said second position to said first position when said door is moved to its closed position, and releasing said shaft for movement to said second position when said door is moved from its closed position, and a wheel frictionally retained on said shaft and positioned adjacent said surface to be engaged by frost forming thereon, said frictional engageclosed position and uncovered by said door when in said open position.

6. The refrigerator defined in claim 4 in which said operating member controls said light bulb to energize said bulb when said door is moved from its closed position and deenergize said light bulb when said door is moved to its closed position.

'7. In a refrigerator cabinet having a food storage chamber, a. cooling unit having a, surface exposed to the air of said chamber, the combination with said surface of a shaft journaled for rotation, said shaft being rotatable between a first and a second position, means for biasing said shaft from said first to said second position, an actuating device responsive to said door for moving said shaft from said second position to said first position when said door is moved to its closed position, said device releasing said member for movement by said biasing means when said door is moved from said closed position, a wheel member on said shaft and in frictional engagement therewith, said frictional engagement being sufficient to prevent movement 'between said shaft and said wheel member by said biasing means but insuiilcient to prevent movement between said shaft and said wheel member by said actuating device, said wheel member lying adjacent said surface of the cooling unit so that frost formed on said surface prevents rotation of said wheel REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,007,409 Schweitzer July 9, 1935 2,112,261 'Backstrom Mar. 29, 1938 

